Oil and natural gas production from offshore platforms represent a substantive component of overall global oil and natural gas production. Such offshore platforms exist in many parts of the world including the North Sea off the coast of northwest Europe, the Gulf of Mexico, and the coast of Brazil, just to name a few. The trend since the early 1930s has been to extend offshore platforms into deeper waters. The typical platforms of the late 1940s were erected in approximately 6 meters or 19.5 feet of water and weighed about 1,100 metric tons or 1,200 tons. Today, platforms can be effected in water over 300 meters or 1000-1,200 feet deep and weigh more than 47,000 metric tons or 52,000 tons.
As these platforms age, produce less oil and natural gas, and/or when the economics do not support continued operations, decommissioning and dismantling these platforms and associated infrastructure present a significant engineering task whereby safety and environmental considerations become very important. Wood Mackenzie, an industry consulting firm in Scotland, “forecasts that the oil industry will spend £15 billion over the next decade on decommissioning in Britain, and that by the early 2020s, annual costs for dismantling fields may exceed new investment.” See Stanley Reed, An Expensive Sunset for the Brent Oil Field, N.Y. Times, Feb. 18, 2015.
These platforms are generally comprised of significant infrastructure below the water level. For example, a platform may be constructed on top of a stable concrete base comprising a plurality of very large tanks. It is not uncommon for a platform to utilize one or more clusters of very large tanks, commonly referred to as “cells,” used for oil storage and/or separation of oil. Access into these tanks may be achieved through the existing interconnected pipes, thereby avoiding access methods which require boring through the structure of the cell and ultimately impacting cell integrity. There is a need to traverse one or more pipes to gain access to the cells for inspection purposes in order to assess various properties of the cells such as, for example, the composition of fluid inside the cells, structural integrity, mapping of the interior of the cells, and sediment accumulation and constituency. Such information derived from a proper inspection of the cells will play an important part in determining if such cells can remain in place on the subsea floor or will have to be removed. The cost differential between these two options is substantial.
As subsea surface operations increase, it is reasonable to assume that a need will exist for inspection of subsea pipes and structures connected to the pipes. Further, as the use of pipes exist in various applications such as pipelines, industrial plants, sewage systems, etc., there will be a need for inspection of said pipes and structures connected thereto.
The present invention provides a means for traversing one or more pipes at least partially filled with a flowing fluid or for subsequently gaining access to a tank at least partially filled with a fluid.